Sol–gel syntheses, luminescence, and energy transfer properties of α-GdB₅O₉:Ce³⁺/Tb³⁺ phosphors

Abstract

Sol-gel method was applied to prepare homogenous and highly crystalline phosphors with the formulas α-GdB5O9:xTb(3+) (0 ≤ x ≤ 1), α-Gd1-xCexB5O9 (0 ≤ x ≤ 0.40), α-GdB5O9:xCe(3+), 0.30Tb(3+) (0 ≤ x ≤ 0.15) and α-GdB5O9:0.20Ce(3+), xTb(3+) (0 ≤ x ≤ 0.10). The success of the syntheses was proved by the linear shrinkage or expansion of the cell volumes against the substitution contents. In α-GdB5O9:xTb(3+), an efficient energy transfer from Gd(3+) to Tb(3+) was observed and there was no luminescence quenching. The exceptionally high efficiency of the f-f excitations of Tb(3+) implies that these phosphors may be good green-emitting UV-LED phosphors. For α-Gd1-xCexB5O9, Ce(3+) absorbs the majority of the energy and transfers it to Gd(3+). Therefore, the co-doping of Ce(3+) and Tb(3+) leads to a significant enhancement in the green emission of Tb(3+). Our current results together with the study on α-GdB5O9:xEu(3+) in the literature indicate that α-GdB5O9 is a good phosphor host with advantages including controllable preparation, diverse cationic doping, the absence of concentration quenching, and effective energy transfer.

The crystal structure and luminescence quenching of poly- and single-crystalline KYW2O8:Tb3+

“…Especially for laser applications the yttrium site is partly replaced by ytterbium or erbium [11,12]. To our surprise, terbium was not studied in this host so far, even though it is an interesting candidate for efficient luminescence due to its small multi-phonon relaxation [13]. In particular, the doping of a low phonon host material like the double tungstate KYW 2 O 8 by Tb 3 þ shall result into efficient green emitting materials [5,10] suitable for dedicated investigations of the luminescence of the 4f-4f levels of Tb 3 þ .…”

Ba6(Bi1−xEux)9B79O138 (0 ≤ x ≤ 1): synergetic changing of the wavelength of Bi3+ absorption and the red-to-orange emission ratio of Eu3+

“…[1][2][3] Their major structural characteristic is the rigid covalent boron-oxygen network. 6,7 REMB 9 O 16 (RE = rare earth, M = Sr or Ba) is a series of wellknown phosphor hosts with the advantage of containing two types of cations, RE 3+ and M 2+ . 4,5 For example, the absence of concentration quenching was reported in Eu 3+and Tb 3+ -doped a-GdB 5 O 9 phosphors.…”

Ambient‐Pressure Stabilization of β‐GdB3O6 by Doping with Bi3+ and Color‐Tunable Emissions by Co‐Doping with Tb3+ and Eu3+: The First Photoluminescence Study of a High‐Pressure Polymorph

“…The difficulty in the prepa-ration of rare-earth borates/polyborates might come from the difference in the rate of diffusion between rare-earth and boron atoms duringt he solid-state reaction process. Therefore, alternative methods in synthetic chemistry were developed, and the successful ones include hydrothermal, [13][14][15][16] boric acid flux, [17][18][19][20][21][22] sol-gel, [21][22][23] and high-temperature/high-pressure methods. [24][25][26][27][28][29][30][31][32][33][34][35][36][37] Hydrothermal and boric acid flux methodsu sually produce single-crystal samples with ah igh crystallinity, however,s ometimes with crystalline water molecules or hydroxylg roups included in the structure, which may possibly lead to photoemission quenching or ad ecline in thermals tability.T he high-temperature/high-pressure method is an extremely powerful methodt od iscover new boratec ompounds, however,i ti sn ot an ideal tool for the preparation of optical materials because the resultant sample is usually obtained in small quantities and, even worse, always contains ah igh level of structurald efects, which significantly reduce the optical responses.…”